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posted by Fnord666 on Friday May 01 2020, @11:04AM   Printer-friendly
from the resistance-is-futile.-/home-will-be-assimilated dept.

Good News:

Linux home directory management is about to undergo major change:

With systemd 245 comes systemd-homed. Along with that, Linux admins will have to change the way they manage users and users' home directories.

[...] Prior to systemd every system and resource was managed by its own tool, which was clumsy and inefficient. Now? Controlling and managing systems on Linux is incredibly easy.

But one of the creators, Leannart Poettering, has always considered systemd to be incomplete. With the upcoming release of systemd 245, Poettering will take his system one step closer to completion. That step is by way of homed.

[...] let's take a look at the /home directory. This is a crucial directory in the Linux filesystem hierarchy, as it contains all user data and configurations. For some admins, this directory is so important, it is often placed on a separate partition or drive than the operating system. By doing this, user data is safe, even if the operating system were to implode.

However, the way /home is handled within the operating system makes migrating the /home directory not nearly as easy as it should be. Why? With the current iteration of systemd, user information (such as ID, full name, home directory, and shell) is stored in /etc/passwd and the password associated with that user is stored in /etc/shadow. The /etc/passwd file can be viewed by anyone, whereas /etc/shadow can only be viewed by those with admin or sudo privileges.

[...] Poettering has decided to make a drastic change. That change is homed. With homed, all information will be placed in a cryptographically signed JSON record for each user. That record will contain all user information such as username, group membership, and password hashes.

Each user home directory will be linked as LUKS-encrypted containers, with the encryption directly coupled to user login. Once systemd-homed detects a user has logged in, the associated home directory is decrypted. Once that user logs out, the home directory is automatically encrypted.

[...] Of course, such a major change doesn't come without its share of caveats. In the case of systemd-homed, that caveat comes by way of SSH. If a systemd-homed home directory is encrypted until a user successfully logs in, how will users be able to log in to a remote machine with SSH?

The big problem with that is the .ssh directory (where SSH stores known_hosts and authorized_keys) would be inaccessible while the user's home directory is encrypted. Of course Poettering knows of this shortcoming. To date, all of the work done with systemd-homed has been with the standard authentication process. You can be sure that Poettering will come up with a solution that takes SSH into consideration.

Older articles:

Will systemd be considered complete once the kernel and boot loader have been absorbed into systemd?


Original Submission

 
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  • (Score: 4, Touché) by The Mighty Buzzard on Friday May 01 2020, @01:22PM (13 children)

    A) My login/uid does exist on that computer if it's networked and using kerberos. Just like yours does on dev now that I got rid of the second entry for you that was confusing kerberos.
    B) I've never had to deal with a situation where I needed my home directory wagged to an air-gapped computer but booting from the drive I'm already wagging along isn't an option.

    --
    My rights don't end where your fear begins.
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  • (Score: 2) by janrinok on Friday May 01 2020, @01:36PM (7 children)

    by janrinok (52) Subscriber Badge on Friday May 01 2020, @01:36PM (#988939) Journal

    Only on that network.

    How do you take a portable drive to a computer NOT on that network and have it install itself so that you still have ownership and access control over all of your files? What if your UID is already in use on that computer? Who would have ownership then? You, or the owner of that UID on the new computer?

    • (Score: 4, Insightful) by The Mighty Buzzard on Friday May 01 2020, @01:55PM (1 child)

      How many admins do you know that want people without a login (either networked or local) having access to a box? It's certainly not an end user feature.

      --
      My rights don't end where your fear begins.
      • (Score: 3, Insightful) by sjames on Sunday May 03 2020, @10:37AM

        by sjames (2882) on Sunday May 03 2020, @10:37AM (#989740) Journal

        And conversely, how often do you want documents important enough to encrypt to become accessible to a strange computer? If you're not willing to make your home directory world r/w and share it on a public network, you won't be too thrilled to plug it in on a strange computer.

    • (Score: 1, Informative) by Anonymous Coward on Friday May 01 2020, @09:12PM (3 children)

      by Anonymous Coward on Friday May 01 2020, @09:12PM (#989197)

      If you're root, it's not a problem. If you're not root, you can't mount the drive anyway.

      • (Score: 3, Informative) by janrinok on Saturday May 02 2020, @07:11AM (2 children)

        by janrinok (52) Subscriber Badge on Saturday May 02 2020, @07:11AM (#989366) Journal
        Incorrect. I can connect a LUKS encrypted drive into any of my Ubuntu/Debian/ computers and it will allow me to decrypt my drive and will automatically mount it in /run/[username]/[drive ID]. I don't have to be root to do that. There is no special configuration necessary.
        • (Score: 1, Insightful) by Anonymous Coward on Saturday May 02 2020, @12:54PM (1 child)

          by Anonymous Coward on Saturday May 02 2020, @12:54PM (#989442)

          That's Ubuntu defaulting to unsecure, not surprising. None of my systems automount anything.

          • (Score: 3, Informative) by janrinok on Sunday May 03 2020, @07:11AM

            by janrinok (52) Subscriber Badge on Sunday May 03 2020, @07:11AM (#989712) Journal

            So if a computer user wants to back up his user area to a thumbdrive or portable disk on your system does he need to go and find an administrator? That doesn't seem very sensible to me.

            On ubuntu the drive is mounted with the same permissions as the user, so the system is still protected posing no more risk than that user has rights to do anyway..

    • (Score: 2, Interesting) by Anonymous Coward on Friday May 01 2020, @09:56PM

      by Anonymous Coward on Friday May 01 2020, @09:56PM (#989226)

      Let me introduce you to encrypted containers on NTFS or ExFAT. Portable. Secure. If you can mount it you can access it. Look into Veracrypt and it will solve your problem without fucking up everything for the rest of us.

  • (Score: 2) by janrinok on Friday May 01 2020, @01:39PM (4 children)

    by janrinok (52) Subscriber Badge on Friday May 01 2020, @01:39PM (#988942) Journal

    Saying that you don't have the need is not solving the problem for those that do. Just because you don't need it doesn't mean nobody else should need it either.

    So I ask again - what is your kerberos and scripting solution, or any solution at all, to that problem?

    • (Score: 3, Insightful) by The Mighty Buzzard on Friday May 01 2020, @01:56PM (3 children)

      That's kind of the point. It's a problem that does not exist.

      --
      My rights don't end where your fear begins.
      • (Score: 2, Informative) by janrinok on Friday May 01 2020, @02:51PM (2 children)

        by janrinok (52) Subscriber Badge on Friday May 01 2020, @02:51PM (#988990) Journal

        Not for you - but there are many who do have this problem.

        • (Score: 5, Touché) by The Mighty Buzzard on Friday May 01 2020, @03:25PM

          Are there? In what situation would any admin want someone who specifically does not have a login (either networked or local) to a system not only able to log in but to bring arbitrary files along for the ride?

          --
          My rights don't end where your fear begins.
        • (Score: 2, Informative) by Anonymous Coward on Friday May 01 2020, @11:17PM

          by Anonymous Coward on Friday May 01 2020, @11:17PM (#989254)

          It doesn't exist for anybody. If people need to have their various IDs matching on different systems, there are multiple solutions to that already. If, you're logging into random computers where your UID and GID aren't matching, you're doing something very, very wrong. Modern systems have various ways in which they can keep UIDs and GIDs consitant across different computers. Try using one of them, they don't require the abomination that is systemd.

          As has already been mentioned, Kerberos is a thing, you can also opt for mounting some or all of /etc over the network with a local backup as failsafe. Ultimately, The developer of this crappy software is either incompetent or an egomaniac. Or, probably both, none of the "problems" he's solving are real problems and they certainly don't require the kind of software kludge he's made.